- It has a mix of wilderness and indoor/dungeon.
- In the mountains, and I had handy mountains.
- It has an interesting mix of monsters, including some of the odder but well-chosen monsters typical to the UK series of adventures.
- It's a sandbox with a plot, which makes it easy to adventure in, with lots of things to do with lots of logical stopping points.
- It has a mix of a plot device that fits into DF (a meteor!) and something DF does well - gnome artificers.
- A mix of combat and negotiation, and plenty of chances to choose between them.

Why I rejected it:

- Maybe a little too much gnome artificer technology.
- It has a lot of fiddly bits, which would make it tricky to convert.
- So much to read, absorb, and have fluency in that it would take some familiarity to be comfortable using it. I didn't have that kind of time.

I may still use this adventure some day - it's really an interesting one, with a lot of interesting hooks and good places to adventure.

- Desert. As good as it was, it's a desert, and I'd decided a desert wasn't going to fit into my plans.
- Theme. I'd have to rename, relabel, and re-purpose some of the material to make it fit with how my world is working. That would take some work to do properly.

- A bit too powerful, if I converted it appropriately.
- A little difficult to convert, because it's been years since I played a CoC-based game system.
- Treasure a bit too rich, magically.
- A bit too small for delve-and-return. To do delve-and-return it would need significant expansion.
- Wilderness too small, so I'd need to create my own.

So out of five, I rejected those four. The other I took and used as the basis - largely intact - but I can't disclose what it is, of course.